Structural effects of variation in the human clavicle

Area of Science:

• Anthropology
• Biomechanics
• Paleoanthropology

Background:

• Evolutionary shifts in shoulder structure are linked to hominin behavior and adaptation.
• Clavicle morphology is used to infer these shifts, but empirical data is lacking.
• This study examines clavicle morphology's effect on human shoulder girdle and upper thorax configuration.

Purpose of the Study:

• To investigate how clavicle morphology influences the articulated shoulder girdle and upper thorax in humans.
• To establish predictive relationships between disarticulated clavicle morphology and articulated shoulder structure.
• To inform the interpretation of skeletal remains and improve reconstructions of ancient hominins.

Main Methods:

• Collected 3D CT scan data of clavicle, scapula, and upper ribs from living humans.
• Utilized partial least squares and regression analyses to assess covariation between disarticulated and articulated morphology.

Main Results:

• Combined clavicle, rib, and scapula dimensions correlate with resting shoulder protraction.
• Shorter clavicles are associated with protracted and elevated scapular resting positions.
• Shoulder breadth is primarily determined by clavicle length and orientation, allowing for reliable reconstruction.

Conclusions:

• Understanding clavicle morphology provides insights into human shoulder structure and variation.
• Predictive equations are provided for inferring shoulder structure from disarticulated clavicles.
• Future research on interspecific variation will enhance skeletal reconstructions for ancient hominins.